The present invention pertains to a lubricant sealing device for the feed dog actuating slide members (hereinafter referred to as slide members) in a sewing machine. The device defines a plate-shaped element having a suitable opening through which one or more actuating slide members are adapted to extent. The shaped element is slidable supported by a pair of spaced and vertically extending guides which are mounted in a flanged support bracket having a cross-sectional configuration that is generally U-shaped. This support bracket includes a longitudinal channel that serves to guide the slide members during the performance of their intended functions and by means of its flanged portion, it is mounted in the framework of the machine in a manner which separates those elements requiring lubricant from those which do not.
It is well known that in certain types of sewing machines the driving mechanisms and associated seats subject to wear require adequate lubrication which makes it necessary to maintain a definite separation between the areas in which the elements being lubricated are operating and the area of the stitching zone so as to prevent migration of lubricant to the stitching instrumentalities which as can be readily understood would be the cause of a very undesirable condition of soiling the workpieces as they are being sewn. It is common practice to provide the casing of the machine with a chamber within which the mechanisms for effecting actuation of the feed dogs are mounted.
As is well known, the feed dogs are located in the sewing zone which is spaced from the chamber and they are supported by slide members which extend from and through a suitable opening provided in one wall of said chamber which defines a surface separating the latter from the area which should be devoid of lubricant. To prevent the lubricant from escaping from the chamber in the area providing clearance for the slide members extending through the opening in the chamber wall, known forms of sealing devices are utilized which have a configuration conforming to the cross-sectional configuration of one or more slide members. Having this configuration, the sealing devices closely surround the slide members and serve as oil scraping elements during operation of said slide members.
The known types of sealing elements have a serious disadvantage of requiring frequent replacement due to wear and are considered to have an undesirable life expectancy. Wear is attributed to the frictional contact of the slide with the walls of the sealing device that define the opening through which said slide extends. Although the thickness of the known type of sealing elements is on the order of 1-2 millimeters as well as the material utilized in their fabrication having a low coefficient of friction, such as Teflon and the fact that the walls defining the opening are fabricated to conform to the cross-sectional configuration of the slide, they soon become worn due to the frictional forces to which they are subjected thus causing them to become curved in the direction of their outer edges, as well as to the rounding off of their edges whereby they are rendered ineffective in operation as oil scraping devices.
To correct this serious disadvantage, an object of the present invention is that of providing a sealing device for the lubricant in which the plate-shaped sealing element possesses characteristics which will provide an improved combination lubricant seal and an oil scraper that will have a substantially greater life expectancy than the known forms of sealing devices.